镁合金中■两种孪晶界面的可动性比较
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摘要
形变孪生是镁合金的主要塑性变形方式之一,镁合金的两种主要孪晶为■孪晶,两种常见孪晶在形貌上存在较大的差异。本文采用分子动力学模拟与微观组织实验观察相结合的手段,研究了两种孪晶压缩过程的应力应变曲线、微观结构以及界面的迁移方式,对比分析两种孪晶界面的可动性。并且从原子运动以及位错滑移的角度,解释两者存在差异的原因。结果表明:■孪晶界迁移所需的应力较■孪晶界迁移所需的应力低,并且■孪晶界的迁移呈现"弓形"方式,而■孪晶界以"台阶"的方式进行迁移。■孪晶界的迁移是B/P面相互转变的过程,因而界面更容易大范围、高速率地迁移;而透射电镜(TEM)观察和模拟结果均显示,■孪晶界面上存在周期性的界面位错,阻碍了孪晶界的移动,并且需有基面位错滑移至孪晶界面处堆积,为■孪晶界的迁移提供能量。
Deformation twinning is one of the main plastic deformation modes of magnesium alloy. Two main types of twin are ■. There have great differences between the morphology of two kinds of common twins.■ tensile twins mostly form in non-basal plane oriented grain. Once the twins have formed, it will expand rapidly,and gradually engulf the matrix. Thus the morphology features of ■ twins are mostly lenticular. However, ■compression twins mostly form in basal plane oriented grain. After the formation of these twins, it is difficult to expand laterally, and the morphology features of ■ twins are mostly narrow-flake. The combination of molecular dynamics method and microstructure experiment observation is used to establish the atomic models of two kinds of twins.In addition, the size and loading mode of the two models are consistent. This paper contrasts the mobility of two kinds of twin interfaces through analysis of stress-strain curve, microstructure and interface migration mode. And the reasons for the difference interface mobility are explained from the point of view of atomic motion and dislocation slip. The simulation and experimental results show that the stress required for ■twin boundary migration is lower than that for ■twin boundary. The migration of ■ twin boundaries presents "bow" shape mode, while ■ twin boundaries migrate with "step" mode. Actually, the migration of ■twin boundaries is the process of mutual transformation of Basal planes and Prism planes. Interestingly, the atomic arrangements of Basal plane and Prism plane are similar, thus it is easy to implement the mutual conversion process. However, it is found that there are periodic interfacial dislocations on the ■ twin interface by TEM observation and simulation results, and the interfacial dislocations will hinder the movement of twin interface. It is also found that there are basal plane dislocation spiling up at the interface; it can provide energy for the migration of ■ twin boundaries. Therefore, ■ twin boundaries are easier to form large-scale and rapid migration than ■ twin boundaries.
Deformation twinning is one of the main plastic deformation modes of magnesium alloy. Two main types of twin are ■. There have great differences between the morphology of two kinds of common twins.■ tensile twins mostly form in non-basal plane oriented grain. Once the twins have formed, it will expand rapidly,and gradually engulf the matrix. Thus the morphology features of ■ twins are mostly lenticular. However, ■compression twins mostly form in basal plane oriented grain. After the formation of these twins, it is difficult to expand laterally, and the morphology features of ■ twins are mostly narrow-flake. The combination of molecular dynamics method and microstructure experiment observation is used to establish the atomic models of two kinds of twins.In addition, the size and loading mode of the two models are consistent. This paper contrasts the mobility of two kinds of twin interfaces through analysis of stress-strain curve, microstructure and interface migration mode. And the reasons for the difference interface mobility are explained from the point of view of atomic motion and dislocation slip. The simulation and experimental results show that the stress required for ■twin boundary migration is lower than that for ■twin boundary. The migration of ■ twin boundaries presents "bow" shape mode, while ■ twin boundaries migrate with "step" mode. Actually, the migration of ■twin boundaries is the process of mutual transformation of Basal planes and Prism planes. Interestingly, the atomic arrangements of Basal plane and Prism plane are similar, thus it is easy to implement the mutual conversion process. However, it is found that there are periodic interfacial dislocations on the ■ twin interface by TEM observation and simulation results, and the interfacial dislocations will hinder the movement of twin interface. It is also found that there are basal plane dislocation spiling up at the interface; it can provide energy for the migration of ■ twin boundaries. Therefore, ■ twin boundaries are easier to form large-scale and rapid migration than ■ twin boundaries.
引文
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[18]胡轶嵩,杨平,赵祖德,马端骋.利用取向成像研究镁合金的孪生过程[J].中国有色金属学报,2004,14(1):105-111.HU Yi-song,YANG Ping,ZHAO Zu-de,MA Duan-cheng.Investigation of twinning process in magnesium alloy by means of orientation mapping[J].The Chinese Journal of Nonferrous Metals,2004,14(1):105-111.
[19]KADIRI H E,BARRETT C D,WANG J,TOMéC N.Why are{1012}twins profuse in magnesium?[J].Acta Mater,2015,85:354-361.
[20]LI B,ZHANG X Y.Twinning with zero twinning shear[J].Scripta Mater,2016,125:73-79.
[21]LENTZ M,RISSE M,SCHAEFER N,REIMERS W,BEYERLEIN I J.Strength and ductility with{1011}-{1012}double twinning in a magnesium alloy[J].Nat Commun,2016,7:11068-11074.
[22]况新亮,刘天模,何杰军.基于镁合金{1012}孪生的织构调整及屈服行为演变[J].中国有色金属学报,2014,24(5):1111-1117.KUANG Xin-liang,LIU Tian-mo,HE Jie-jun.Evolution of texture and yielding behavior induced by{1012}twinning of magnesium alloy[J].The Chinese Journal of Nonferrous Metals,2014,24(5):1111-1117.
[23]娄超,张喜燕,汪润红,段高林,刘庆.退孪生行为以及{1012}孪晶片层结构对镁合金力学性能的影响[J].金属学报,2013,49(3):291-296.LOU Chao,ZHANG Xi-yan,WANG Run-hong,DUANGao-lin,LIU Qing.Effects of untwining and{1012}twin lamellar structure on the mechanical properties of Mg alloy[J].Acta Metall Sin,2013,49(3):291-296.
[24]杨续跃,张雷.镁合金温变形过程中的孪生及孪晶交叉[J].金属学报,2009,45(11):1303-1308.YANG Xu-yue,ZHANG Lei.Twinning and twin intersection in AZ31 Mg alloy during warm deformation[J].Acta Metall Sin,2009,45(11):1303-1308.
[25]SUN D Y,MENDELEV M I,BECKER C A,KUDIN K,HAXHIMALI T,ASTA M,HOYT J J,KARMA A,SROLOVITZ D J.Crystal-melt interfacial free energies in hcp metals:A molecular dynamics study of Mg[J].Phys Rev B,2006,73(2):024116.
[26]PLIMPTON S.Fast parallel algorithms for short-range molecular dynamics[J].Journal of Computational Physics,1995,117(1):1-19.
[27]STUKOWSKI A.Visualization and analysis of atomistic simulation data with OVITO-The open visualization tool[J].Modelling Simul Mater Sci Eng,2010,18(6):2154-2162.
[28]TU J,ZHANG S.On the{1012}twinning growth mechanism in hexagonal close-packed metals[J].Materials&Design,2016,96:143-149.
[29]LIU B Y,WANG J,LI B,LU L,ZHANG X Y,SHAN Z W,LI J,JIA C L,SUN J,MA E.Twinning-like lattice reorientation without a crystallographic twinning plane[J].Nat Commun,2014,5(2):3297-3302.
[2]ROBERT S B.Magnesium products design[M].USA:The International Magnesium Association,1987:373-375.
[3]丁文江.镁合金科学与技术[M].北京:科学出版社,2007:25-30.DING Wen-jiang.Science and technology of magnesium alloys[M].Beijing:Science Press,2007:25-30.
[4]DUDAMELL N V,ULACIA I,GáLVEZ F,YI S,BOHLENJ,LETZIG D,HURTADOB I,PéREZ-PRADOA M T.Twinning and grain subdivision during dynamic deformation of a Mg AZ31 sheet alloy at room temperature[J].Acta Mater,2011,59(18):6949-6962.
[5]SANDL?BESS,ZAEFFERER S,SCHESTAKOW I,YI S,GONZALEZ-MARTINEZ R.On the role of non-basal deformation mechanisms for the ductility of Mg and Mg-Yalloys[J].Acta Mater,2011,59(2):429-439.
[6]ZHANG F,HAO M,WANG F C,TAN C W,YU X D,MA HL,CAI H N.Role of{1012}twinning and detwinning in the shock-hardening behavior of rolled Mg-3Al-1Zn alloy[J].Scripta Mater,2012,67(12):951-954.
[7]CHRISTIAN J W,MAHAJAN S.Deformation twinning[J].Progress in Materials Science,1995,39(1):1-157.
[8]YOO M H.Slip,twinning,and fracture in hexagonal close-packed metals[J].Metallurgical Transactions A,1981,12(3):409-418.
[9]刘庆.镁合金塑性变形机理研究进展[J].金属学报,2010,46(11):1458-1472.LIU Qing.Research progress on plastic deformation mechanism of Mg alloys[J].Acta Metall Sin,2010,46(11):1458-1472.
[10]单智伟,刘博宇.Mg的{1012}形变孪晶机制[J].金属学报,2016,52(10):1267-1278.SHAN Zhi-wei,LIU Bo-yu.The mechanism of{1012}deformation twinning in magnesium[J].Acta Metall Sin,2016,52(10):1267-1278.
[11]涂坚,周志明,柴林江,黄灿.密排六方金属{1012}形变孪晶长大机制的研究进展[J].中国有色金属学报,2015,25(9):2317-2325.TU Jian,ZHOU Zhi-ming,CHAI Lin-jiang,HUANG Can.Research progress on growth mechanism of{1012}twin in hexagonal close packed metals[J].The Chinese Journal of Nonferrous Metals,2015,25(9):2317-2325.
[12]汪炳叔,邓丽萍,CHAPUIS A,郭宁,李强.AZ31镁合金在平面应变压缩过程中的孪生行为研究[J].金属学报,2015,51(12):1441-1448.WANG Bing-shu,DENG Li-ping,CHAPUIS A,GUO Ning,LI Qiang.Study of twinning behavior of AZ31 Mg alloy during plane strain compression[J].Acta Metall Sin,2015,51(12):1441-1448.
[13]OSTAPOVETS A,SERRA A.Slip dislocation and twin nucleation mechanisms in hcp metals[J].Journal of Materials Science,2017,52(1):533-540.
[14]LECLERCQ L,CAPOLUNGO L,Rodney D.Atomic-scale comparison between twin growth mechanisms in magnesium[J].Materials Research Letters,2014,2(3):152-159.
[15]XU Hong-lu,SU Xiao-ming,YUAN Guang-yin,JINZhao-hui.Primary and secondary modes of deformation twinning in HCP Mg based on atomistic simulations[J].Transactions of Nonferrous Metals Society of China,2014,24(12):3804-3809.
[16]刘筱,朱必武,李落星,唐昌平.挤压态AZ31镁合金热变形过程中的孪生和织构演变[J].中国有色金属学报,2016,26(2):288-295.LIU Xiao,ZHU Bi-wu,LI Luo-xing,TANG Chang-ping.Twinning and texture evolution in extruded AZ31magnesium alloy during hot deformation[J].The Chinese Journal of Nonferrous Metals,2016,26(2):288-295.
[17]娄超,张喜燕,任毅.动态塑性变形下AZ31镁合金的孪生特征[J].中国有色金属学报,2015,25(10):2642-2648.LOU Chao,ZHANG Xi-yan,REN Yi.Twinning characteristic of AZ31 magnesium alloy during dynamic plastic deformation[J].The Chinese Journal of Nonferrous Metals,2015,25(10):2642-2648.
[18]胡轶嵩,杨平,赵祖德,马端骋.利用取向成像研究镁合金的孪生过程[J].中国有色金属学报,2004,14(1):105-111.HU Yi-song,YANG Ping,ZHAO Zu-de,MA Duan-cheng.Investigation of twinning process in magnesium alloy by means of orientation mapping[J].The Chinese Journal of Nonferrous Metals,2004,14(1):105-111.
[19]KADIRI H E,BARRETT C D,WANG J,TOMéC N.Why are{1012}twins profuse in magnesium?[J].Acta Mater,2015,85:354-361.
[20]LI B,ZHANG X Y.Twinning with zero twinning shear[J].Scripta Mater,2016,125:73-79.
[21]LENTZ M,RISSE M,SCHAEFER N,REIMERS W,BEYERLEIN I J.Strength and ductility with{1011}-{1012}double twinning in a magnesium alloy[J].Nat Commun,2016,7:11068-11074.
[22]况新亮,刘天模,何杰军.基于镁合金{1012}孪生的织构调整及屈服行为演变[J].中国有色金属学报,2014,24(5):1111-1117.KUANG Xin-liang,LIU Tian-mo,HE Jie-jun.Evolution of texture and yielding behavior induced by{1012}twinning of magnesium alloy[J].The Chinese Journal of Nonferrous Metals,2014,24(5):1111-1117.
[23]娄超,张喜燕,汪润红,段高林,刘庆.退孪生行为以及{1012}孪晶片层结构对镁合金力学性能的影响[J].金属学报,2013,49(3):291-296.LOU Chao,ZHANG Xi-yan,WANG Run-hong,DUANGao-lin,LIU Qing.Effects of untwining and{1012}twin lamellar structure on the mechanical properties of Mg alloy[J].Acta Metall Sin,2013,49(3):291-296.
[24]杨续跃,张雷.镁合金温变形过程中的孪生及孪晶交叉[J].金属学报,2009,45(11):1303-1308.YANG Xu-yue,ZHANG Lei.Twinning and twin intersection in AZ31 Mg alloy during warm deformation[J].Acta Metall Sin,2009,45(11):1303-1308.
[25]SUN D Y,MENDELEV M I,BECKER C A,KUDIN K,HAXHIMALI T,ASTA M,HOYT J J,KARMA A,SROLOVITZ D J.Crystal-melt interfacial free energies in hcp metals:A molecular dynamics study of Mg[J].Phys Rev B,2006,73(2):024116.
[26]PLIMPTON S.Fast parallel algorithms for short-range molecular dynamics[J].Journal of Computational Physics,1995,117(1):1-19.
[27]STUKOWSKI A.Visualization and analysis of atomistic simulation data with OVITO-The open visualization tool[J].Modelling Simul Mater Sci Eng,2010,18(6):2154-2162.
[28]TU J,ZHANG S.On the{1012}twinning growth mechanism in hexagonal close-packed metals[J].Materials&Design,2016,96:143-149.
[29]LIU B Y,WANG J,LI B,LU L,ZHANG X Y,SHAN Z W,LI J,JIA C L,SUN J,MA E.Twinning-like lattice reorientation without a crystallographic twinning plane[J].Nat Commun,2014,5(2):3297-3302.